[mythtv-users] Blurring

Remco Treffkorn remco at rvt.com
Thu May 31 05:04:50 UTC 2007

On Wednesday 30 May 2007, William Munson wrote:
> norman wrote:
> > I am very new to looking at TV on the computer and I am quite happy with
> > the result. There is one thing, however, on which I would welcome an
> > opinion. Whenever there is rapid movement, such as scrolling captions,
> > noticeable blurring takes place of the moving images. Is this a function
> > of the video card and, if so, how should it be addressed?
> >
> > Norman
> If you are viewing on a LCD monitor rather than an old picture tube
> monitor the blurring is due to the response time of your monitor. This
> is very common with monitors as they are designed to "hold" the picture
> for a short time. This prevents flickering on normal computer viewing
> but is not desirable on a tv picture.

There is just a kernel of truth in this false statement, that it makes me 

Yes, in the early days computer monitors had slow phosphors to minimize 
flickering caused by slow refresh rates. We are talking early eighties.

TV screens have the same problem. You want the pixel to last a bit to minimize 
flickering, but not too long, to avoid the "trailing light tail" effect.

TFT LCD's are very different. For them it takes a finite time to change 
luminosity/color. You are talking around 8 to 16 ms. Not even in the same 
ballpark as the slow phosphors we were taking about.

Nowadays motion blur is more likely caused by the mpeg codec used, or just 
present in the source already. Watching POTV on a modern high res LCD just 
exposes problems that were always there.

BTW, this is not meant as a complete and correct explanation of what's going 
on, just an encouragement to google, if you want the full explanation.


Remco Treffkorn (RT445)
remco at rvt.com   (831) 685-1201

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